The present invention relates to methods for treating gestational diabetes mellitus comprising administration of an effective amount of an exendin or an exendin agonist alone or in conjunction with other compounds or compositions that affect blood glucose control, such as an insulin or an amylin agonist. Pharmaceutical compositions for use in the methods of the invention are also disclosed.
The following description summarizes information relevant to the present invention. It is not an admission that any of the information provided herein is prior art to the presently claimed invention, nor that any of the publications specifically or implicitly referenced are prior art to that invention.
Gestational diabetes mellitus (xe2x80x9cGDMxe2x80x9d) is a disorder associated with elevated circulating plasma glucose. Although the diagnostic criteria for GDM have been the subject of controversy for decades, it was defined by the Third Workshop Conference on Gestational Diabetes Mellitus as carbohydrate intolerance of varying severity with onset or first recognition during pregnancy, irrespective of the glycemic status after delivery. Metzger (ed.) Proceedings of the Third International Workshop Conference on Gestational Diabetes Mellitus, Diabetes 40(Suppl. 2), 1991. Despite advances in clinical management of GDM, there are problems associated with GDM which persist, including elevated rate of perinatal morbidity and elevated rate of malformations in newborns. Persson et al., Diabetes and Pregnancy, In International Textbook of Diabetes Mellitus, Second Edition, John Wiley and Sons 1997 (Alberti et al. Eds.). For example, it has been reported that, when the mean blood glucose level is greater than 105 mg/dl, there is a greater risk for the development of large-for-gestational age (xe2x80x9cLGAxe2x80x9d) infants when compared with a control population. Id. Additional reported consequences of untreated GDM include an increased incidence of macrosomia, respiratory distress syndrome, and other abnormalities of fetal metabolism. Langer, Am. J. Obstet Gynecol. 176:S186, 1997; American Diabetes Association: Self-Monitoring of Blood Glucose Consensus Statement, Diabetes Care 17:81-82, 1994(xe2x80x9cABA Consensus Statementxe2x80x9d); Coetzee and Jackson, S. Afr. Med. J. 56:467-475, 1979. It has been clearly established by those in the field that tight glycemic control can serve as the primary prevention of fetal disease relating to GDM. Drexel et al., Diabetes Care 11:761-768, 1988; Roversi et al., Diabetes Care 3:489-494, 1980; Langer and Mazze, Am. J. Obstet Gynecol. 159:1478-1483, 1988; Langer et al., Am. J. Obstet Gynecol. 161:646-653, 1989). GDM results in a greater incidence of intrauterine death or neonatal mortality. Position Statement American Diabetes Association: Gestational Diabetes Mellitus, Diabetes Care 21 (Suppl. 1):S60-61, 1998. GDM pregnancies are at an increased risk for fetal macrosomia and neonatal morbidities including neural tube defects, hypoglycemia, hypocalcemiea, hypomagnsemia, polycythemia and hyperbilirubinemia and subsequent childhood and adolescent obesity. Siccardi, Gestational Diabetes. Other complications to the woman include increased rates of cesarean delivery, hypertensive disorders including preeclamsia and urinary tract infections.
It has been reported that approximately 4% of all pregnancies (135,000 cases annually) are complicated by GDM, however, it has been estimated that the incidence may range from 1% to 14% of all pregnancies, depending on the population and diagnostic tests employed. ADA Consensus Statement, supra.
Normally during pregnancy, fasting plasma levels of insulin gradually increase to reach concentrations that are approximately twice as high in the third trimester as they were outside of pregnancy. Women with gestational diabetes mellitus (xe2x80x9cGDMxe2x80x9d) have fasting insulin levels comparable to or higher than those of normal pregnant women with the highest levels seen in women with GDM who are obese. Insulin secretion also increases gradually in pregnancy and also reaches a maximum during the third trimester. However, the relative increase in secretion is significantly smaller in women with GDM than in normal glucose tolerant (xe2x80x9cNGTxe2x80x9d) women. The first-phase insulin response in NGT women is significantly higher than in GDM women; second phase insulin response was similarly increased during pregnancy in both groups. This finding is consistent with the finding that GDM women have a later time of peak insulin concentration during an oral glucose tolerance test than do NGT women. Consistent with this observation, the insulin response per unit of glycemic stimulus is significantly higher in NGT women than in GDM women (90% and 40%, respectively). The fact that glucose tolerance deteriorates in both normal and GDM pregnancies while at the same time, insulin secretion increases indicates a decrease in insulin sensitivity. Comparative results from an intravenous glucose tolerance test and a hyperinsulinemic, euglycemic clamp showed a sensitivity decrease during pregnancy in both groups of 50-60%, but GDM women had a slightly lower sensitivity. In another study using radioactive glucose, turnover of glucose and amino acids in GDM women was comparable to NGT women only when insulin concentrations 3-5 fold higher in the GDM group were used. Thus, it appears that GDM is due to a combination of diminished insulin sensitivity and an impaired ability to increase insulin secretion and has, in fact, many features in common with type 2 diabetes. Normal or near normal glycemic control returns upon parturition.
Clinical Diagnosis
It is common clinical practice to screen women for elevated glucose and glucose intolerance between weeks 24 and 28 of gestation, especially women with any one the following four characteristics: age xe2x89xa725; race/ethnicity of Hispanic, Native American, Asian, African-American or Pacific Islander origin; obese or a family history of diabetes. In addition, women with previous pregnancies with complications due to a large weight fetus/neonate are usually tested. In some medical centers all pregnant women are tested. Indeed, certain investigators have found that historical risk factors account for only roughly half of the women known to have GDM. Carr, Diabetes Care 21(Suppl. 2):B14-B18, 1998. Additionally, there is some reported evidence that advancing maternal age is associated with increased incidence of GDM. Id.
The clinical diagnosis is generally based on a multi-step process. The evaluation is most typically performed by measuring plasma glucose 1 hour after a 50-gram oral glucose challenge test in either the fasted or the unfasted state. If the value in the glucose challenge test is xe2x89xa7140 mg/dl, a 3-hr 100 g oral glucose tolerance test is done. If two or more of the following criteria are met, the patient is considered in need of glycemic control: fasted venous plasma xe2x89xa7105 mg/dl, venous plasma xe2x89xa7190 mg/dl at 1 hr, venous plasma xe2x89xa7165 mg/dl at 2 hr or venous plasma xe2x89xa7145 mg/dl at 3 hr. Williams et al., Diabetes Care 22: 418-421, 1999. Variations of this test are also used by some. See, e.g., Coustan, Gestational Diabetes In Diabetes in America, 2d ed. National Institutes of Health Publication No. 95-1468, 1995.
Current Clinical Therapy
The current therapeutic approach for GDM is to control plasma glucose for the remainder of the gestation (i.e., the third trimester through parturition). GDM has many features in common with type 2 diabetes. The endocrine (impaired insulin secretion) and metabolic (insulin resistance) abnormalities that characterize both forms of diabetes are similar. In general, pregnancy is characterized by increases in both insulin resistance and insulin secretion. Women with GDM fail to respond with increased insulin to the decrease in insulin sensitivity.
A significant correlation has been shown to exist between late-stage gestational maternal glucose levels and preeclamsia, macrosomia, Cesarean section delivery and phototherapy for hyperbilirubinemia. Sermer et al., Diabetic Care 21 (Suppl. 2):B33-B42, 1998. It has also been determined that the length of hospitalization of the new mother and the length of time the neonate spent in the nursery could be correlated to the degree of elevation of plasma glucose in the pregnant woman. Id. Tallarigo, et al. reported a striking rise in the risk of fetal macrosomia (9.9 vs. 27.5%) and preeclamsia/Cesarean sections (19.9 vs. 40.0%) in women with abnormal glucose tolerance when compared to NGT women. Tallarigo et al., N. Engl. J. Med. 315:989-992, 1986.
Thus, the goals for therapy of GDM are to achieve and maintain as near normal glycemia as feasible with a special emphasis to keep postprandial glucose concentrations within the normal range. Optimal therapeutic strategies are safe and efficacious in achieving a metabolic balancing without creating complications, which may include ketosis and/or hypoglycemia. Jovanovic, Diabetes Care 21(Suppl. 2):B131-B137, 1998. The initial therapeutic approach is through diet. Jovanovic-Peterson and Peterson, J. Am. Coll. Nutr. 9:320-325, 1990.
If diet or diet and exercise are not effective (i.e., failure is fasting glucose xe2x89xa7105 mg/dl and/or a 2-hr postprandial plasma glucose of xe2x89xa7120 mg/dl on 2 or more occasions within a 1- to 2-week period), then insulin therapy (preferably, human insulin) is considered appropriate. ADA Position Statement, supra.
Oral glucose-lowering agents are not recommended during pregnancy. Kuhl et al., Diabetic Care 21 (Suppl. 2): B19-B26, 1998. Although sulfonylureas are used in the treatment of type 2 diabetes due to their activity in increasing insulin sensitivity, these agents are contraindicated for use in GDM. Jovanovic, Diabetes Care 21 (Suppl. 2):B131-B137, 1998. See also Kahn and Shechter, Insulin, Oral Hypoglycemic Agents, and the Pharmacology of the Endocrine Pancreas, In Goodman and Gilman""s The Pharmacological Basis of Therapeutics (8th ed. 1993 Goodman Gilman et al. eds.). Oral hypoglycemic drugs traverse the placenta, and may cause prolonged severe hypoglycemia in the newborn. Persson et al., supra.
The difficulties with, and the highly variable approaches to insulin therapy in GDM have been reviewed, for example, by Langer, et al. Langer, Diabetes Care 21(Suppl.2):B91-B98, 1998. The problems commonly associated with insulin therapy in a non-pregnant population remain when used in the treatment of GDM. They are determination of the proper dose, maintenance of good glucose control through each 24-hr period, possible hypoglycemia and weight gain. Hypoglycemia can result when insulin is administered to control postprandial plasma glucose, but the fetus demands for energy in the presence of excess insulin later causes the glucose level to drop to a hypoglycemic level. This physiological state can be dangerous to both the mother and the fetus. Excess weight gain is undesirable in any pregnancy. Another problem with insulin therapy is the day-to-day and week-to-week variability in glucose control vs.insulin dose.
Thus, it can be appreciated that an effective means to treat gestational diabetes remains a major challenge and a superior method of treatment would be of great utility. Such a method, and compounds and compositions which are useful therefor, have been invented and are described and claimed herein.
Exendins are peptides that were first isolated from the salivary secretions of the Gila-monster, a lizard found in Arizona, and the Mexican Beaded Lizard. Exendin-3 is present in the salivary secretions of Heloderma horridum, and exendin-4 is present in the salivary secretions of Heloderma suspectum (Eng, J., et al., J. Biol. Chem., 265:20259-62, 1990; Eng., J., et al., J. Biol. Chem., 267:7402-05, 1992). The exendins have some sequence similarity to several members of the glucagon-like peptide family, with the highest homology, 53%, being to GLP-1[7-36]NH2 (Goke, et al., J. Biol. Chem., 268:19650-55, 1993). GLP-1[7-36]NH2, also known as proglucagon[78-107] and most commonly as xe2x80x9cGLP-1,xe2x80x9d has an insulinotropic effect, stimulating insulin secretion from pancreatic xcex2-cells; GLP-1 also inhibits glucagon secretion from pancreatic xcex1-cells (Orskov, et al., Diabetes, 42:658-61, 1993; D""Alessio, et al., J. Clin. Invest., 97:133-38, 1996). GLP-1 is reported to inhibit gastric emptying (Williams B, et al., J Clin Encocrinol Metab 81 (1): 327-32, 1996; Wettergren A, et al., Dig Dis Sci 38 (4): 665-73, 1993), and gastric acid secretion. (Schjoldager B T, et al., Dig Dis Sci 34 (5): 703-8, 1989; O""Halloran D J, et al., J Endocrinol 126 (1): 169-73, 1990; Wettergren A, et al., Dig Dis Sci 38 (4): 665-73, 1993). GLP-1[7-37], which has an additional glycine residue at its carboxy terminus, also stimulates insulin secretion in humans (Orskov, et al., Diabetes, 42:658-61, 1993). A transmembrane G-protein adenylate-cyclase-coupled receptor believed to be responsible for the insulinotropic effect of GLP-1 is reported to have been cloned from a xcex2-cell line (Thorens, Proc. Natl. Acad. Sci. USA 89:8641-45 (1992)).
Exendin-4 potently binds at GLP-1 receptors on insulin-secreting xcex2TC1 cells, at dispersed acinar cells from guinea pig pancreas, and at parietal cells from stomach; the peptide is also said to stimulate somatostatin release and inhibit gastrin release in isolated stomachs (Goke, et al., J. Biol. Chem. 268:19650-55, 1993; Schepp, et al., Eur. J. Pharmacol., 69:183-91, 1994; Eissele, et al., Life Sci., 55:629-34, 1994). Exendin-3 and exendin-4 were reported to stimulate cAMP production in, and amylase release from, pancreatic acinar cells (Malhotra, R., et al., Regulatory Peptides,41:149-56, 1992; Raufman, et al., J. Biol. Chem. 267:21432-37, 1992; Singh, et al., Regul. Pept. 53:47-59, 1994). The use of exendin-3 and exendin-4 as insulinotrophic agents for the treatment of diabetes mellitus and the prevention of hyperglycemia has been proposed (Eng, U.S. Pat. No. 5,424,286).
C-terminally truncated exendin peptides such as exendin-4[9-39], a carboxyamidated molecule, and fragments 3-39 through 9-39 have been reported to be potent and selective antagonists of GLP-1 (Goke, et al., J. Biol. Chem., 268:19650-55, 1993; Raufman, J. P., et al., J. Biol. Chem. 266:2897-902, 1991; Schepp, W., et al., Eur. J. Pharm. 269:183-91, 1994; Montrose-Rafizadeh, et al., Diabetes, 45(Suppl. 2):152A, 1996). Exendin-4[9-39] is said to block endogenous GLP-1 in vivo, resulting in reduced insulin secretion. Wang, et al., J. Clin. Invest., 95:417-21, 1995; D""Alessio, et al., J. Clin. Invest., 97:133-38, 1996). The receptor apparently responsible for the insulinotropic effect of GLP-1 has reportedly been cloned from rat pancreatic islet cell (Thorens, B., Proc. Natl. Acad. Sci. USA 89:8641-8645, 1992). Exendins and exendin-4[9-39] are said to bind to the cloned GLP-1 receptor (rat pancreatic xcex2-cell GLP-1 receptor (Fehmann H C, et al., Peptides 15 (3): 453-6, 1994) and human GLP-1 receptor (Thorens B, et al., Diabetes 42 (11): 1678-82, 1993). In cells transfected with the cloned GLP-1 receptor, exendin-4 is reportedly an agonist, i.e., it increases cAMP, while exendin[9-39] is identified as an antagonist, i.e., it blocks the stimulatory actions of exendin-4 and GLP-1. Id.
Exendin-4[9-39] is also reported to act as an antagonist of the full length exendins, inhibiting stimulation of pancreatic acinar cells by exendin-3 and exendin-4 (Raufman, et al., J. Biol. Chem. 266:2897-902, 1991; Raufman, et al., J. Biol. Chem., 266:21432-37, 1992). It is also reported that exendin[9-39] inhibits the stimulation of plasma insulin levels by exendin-4, and inhibits the somatostatin release-stimulating and gastrin release-inhibiting activities of exendin-4 and GLP-1 (Kolligs, F., et al., Diabetes, 44:16-19, 1995; Eissele, et al., Life Sciences, 55:629-34, 1994).
Methods for regulating gastrointestinal motility using exendin agonists are described and claimed in U.S. application Ser. No. 08/908,867, filed Aug. 8, 1997, entitled, xe2x80x9cMethods for Regulating Gastrointestinal Motility,xe2x80x9d which application is a continuation-in-part of U.S. application Ser. No. 08/694,954, filed Aug. 8, 1996, which enjoys common ownership with the present invention and is hereby incorporated by reference.
Methods of reducing food intake using exendin agonists are described and claimed in U.S. application Ser. No. 09/003,869, filed Jan. 7, 1998, entitled, xe2x80x9cUse of Exendin and Agonists Thereof for the Reduction of Food Intake,xe2x80x9d claiming the benefit of Provisional Application No. 60/034,905, filed Jan. 7, 1997, No. 60/055,404, filed Aug. 7, 1997, No. 60/065,442 filed Nov. 14, 1997, and No. 60/066,029 filed Nov. 14, 1997. These applications also enjoy common ownership with the present invention and are hereby incorporated by reference.
Exendins have also been found to have inotropic and diuretic effects. International Application No. PCT/US99/02554, filed Feb. 5, 1999, 1998, claiming the benefit of Provisional Application No. 60/075,122, filed Feb. 13, 1998. These applications also enjoy common ownership with the present invention and are hereby incorporated by reference.
Additionally, exendins have been found to suppress glucagon secretion (U.S. Provisional Application No. 60/132,017, entitled, xe2x80x9cMethods for Glucagon Suppression,xe2x80x9d filed Apr. 30, 1999, which enjoys common ownership with the present invention and is hereby incorporated by reference).
Exendin [9-39] has been used to investigate the physiological relevance of central GLP-1 in control of food intake (Turton, M. D. et al. Nature 379:69-72, 1996). GLP-1 administered by intracerebroventricular injection inhibits food intake in rats. This satiety-inducing effect of GLP-1 delivered ICV is reported to be inhibited by ICV injection of exendin [9-39] (Turton, supra). However, it has been reported that GLP-1 does not inhibit food intake in mice when administered by peripheral injection (Turton, M. D., Nature 379:69-72, 1996; Bhavsar, S. P., Soc. Neurosci. Abstr. 21:460 (188.8), 1995).
The present invention concerns the surprising discovery that exendins and exendin agonists do not cross the placenta, and yet have a profound and prolonged effect on blood glucose, rendering them ideal agents for the treatment of gestational diabetes mellitus.
The present invention is directed to novel methods for treating gestational diabetes mellitus comprising the administration of an exendin, for example, exendin-3 [SEQ ID NO. 1: His Ser Asp Gly Thr Phe Thr Ser Asp Leu Ser Lys Gln Met Glu Glu Glu Ala Val Arg Leu Phe Ile Glu Trp Leu Lys Asn Gly Gly Pro Ser Ser Gly Ala Pro Pro Pro Ser], or exendin-4 [SEQ ID NO. 2: His Gly Glu Gly Thr Phe Thr Ser Asp Leu Ser Lys Gln Met Glu Glu Glu Ala Val Arg Leu Phe Ile Glu Trp Leu Lys Asn Gly Gly Pro Ser Ser Gly Ala Pro Pro Pro Ser], or other compounds which effectively bind to the receptor at which exendin exerts its actions which are beneficial in the treatment of gestational diabetes mellitus.
In a first aspect, the invention features a method of treating gestational diabetes mellitus in a subject comprising administering to the subject a therapeutically effective amount of an exendin or an exendin agonist. By an xe2x80x9cexendin agonistxe2x80x9d is meant a compound that mimics the effects of exendin in the treatment of gestational diabetes mellitus by binding to the receptor or receptors where exendin causes one or more of these effects. Exendins and exendin agonist should be especially beneficial in the treatment of GDM because, due to their actions to inhibit gastric emptying, administration of such compounds should not result in increased weight gain. Additionally, in animal and human studies to date, administration of exendins and exendin agonists have not resulted in an increased incidence of hypoglycemia.
Exendin agonist compounds include exendin acids, for example exendin-3 acid and exendin-4 acid. Preferred exendin agonist compounds include those described in International Application No. PCT/US98/16387, entitled, xe2x80x9cNovel Exendin Agonist Compounds,xe2x80x9d filed Aug. 6, 1998, claiming the benefit of U.S. Provisional Patent Application Serial No. 60/055,404, entitled, filed Aug. 8, 1997; International Application No. PCT/US98/24210 entitled, xe2x80x9cNovel Exendin Agonist Compounds,xe2x80x9d filed Nov. 13, 1998, claiming priority on U.S. Provisional Patent Application Serial No. 60/065,442, filed Nov. 14, 1997; and International Application No. PCT/US98/24273 entitled, xe2x80x9cNovel Exendin Agonist Compounds,xe2x80x9d filed Nov. 13, 1998, claiming priority on United States U.S. Provisional Patent Application Serial No. 60/066,029, filed Nov. 14, 1997; all of which enjoy common ownership with the present application and all of which are incorporated by this reference into the present application as though fully set forth herein. Additional preferred exendin agonist compounds are those described and claimed in U.S. Provisional Application Serial No. 60/132,018, entitled, xe2x80x9cModified Exendins and Exendin Agonists,xe2x80x9d filed Apr. 30, 1999, which enjoys common ownership with the present application and which is incorporated by this reference into the present application as though fully set forth herein.
By xe2x80x9cgestational diabetes mellitusxe2x80x9d or xe2x80x9cGDMxe2x80x9d is meant any degree of glucose intolerance with onset or first recognition during pregnancy.
Thus, in a first embodiment, the present invention provides a method for treating gestational diabetes in a subject comprising administering to said subject a therapeutically effective amount of an exendin or an exendin agonist. Preferred exendin agonist compounds include those described in International Application Nos. PCT/US98/16387, PCT/US98/24210, and PCT/US98/24273, which have been incorporated by reference in the present application. Preferably, the subject is a vertebrate, more preferably a mammal, and most preferably a human woman. In preferred aspects, the exendin or exendin agonist is administered parenterally, more preferably by injection. In a most preferred aspect, the injection is a peripheral injection. Preferably, about 1 xcexcg-30 xcexcg to about 1 mg of the exendin or exendin agonist is administered per day. More preferably, about 1-30 xcexcg to about 500 xcexcg, or about 1-30 xcexcg to about 50 xcexcg of the exendin or exendin agonist is administered per day. Most preferably, about 3 xcexcg to about 50 xcexcg of the exendin or exendin agonist is administered per day.
In one preferred aspect, the exendin or exendin agonist used in the methods of the present invention is exendin-3. In another preferred aspect, said exendin is exendin-4. Other preferred exendin agonists include exendin-4 (1-30) [SEQ ID NO 6: His Gly Glu Gly Thr Phe Thr Ser Asp Leu Ser Lys Gln Met Glu Glu Glu Ala Val Arg Leu Phe Ile Glu Trp Leu Lys Asn Gly Gly], exendin-4 (1-30) amide [SEQ ID NO 7: His Gly Glu Gly Thr Phe Thr Ser Asp Leu Ser Lys Gln Met Glu Glu Glu Ala Val Arg Leu Phe Ile Glu Trp Leu Lys Asn Gly Gly-NH2], exendin-4 (1-28) amide [SEQ ID NO 40: His Gly Glu Gly Thr Phe Thr Ser Asp Leu Ser Lys Gln Met Glu Glu Glu Ala Val Arg Leu Phe Ile Glu Trp Leu Lys Asn-NH2], 14Leu,25Phe exendin-4 amide [SEQ ID NO 9: His Gly Glu Gly Thr Phe Thr Ser Asp Leu Ser Lys Gln Leu Glu Glu Glu Ala Val Arg Leu Phe Ile Glu Phe Leu Lys Asn Gly Gly Pro Ser Ser Gly Ala Pro Pro Pro Ser-NH2], 14Leu, 25Phe exendin-4 (1-28) amide [SEQ ID NO 41: His Gly Glu Gly Thr Phe Thr Ser Asp Leu Ser Lys Gln Leu Glu Glu Glu Ala Val Arg Leu Phe Ile Glu Phe Leu Lys Asn-NH2], and 14Leu, 22Ala, 25Phe exendin-4 (1-28) amide [SEQ ID NO 8: His Gly Glu Gly Thr Phe Thr Ser Asp Leu Ser Lys Gln Leu Glu Glu Glu Ala Val Arg Leu Ala Ile Glu Phe Leu Lys Asn-NH2].
In the methods of the present invention, the exendins and exendin agonists may be administered separately or together with one or more other compounds and compositions that exhibit a long-term or short-term blood glucose control action, including, but not limited to other compounds and compositions that comprise an insulin or an amylin agonist. Suitable amylin agonists include, for example, [25,28,29Pro-]-human amylin (also known as xe2x80x9cpramlintide,xe2x80x9d previously referred to as xe2x80x9cAC-137,xe2x80x9d and, referred to in its acetate salt form by its trademark SYMLIN(trademark) (pramlintide acetate), as described in xe2x80x9cAmylin Agonist Peptides and Uses Therefor,xe2x80x9d U.S. Pat. No. 5,686,411, issued Nov. 11, 1997, and salmon calcitonin.